Bourdon-tube spring



J. C. SHAW BOURBON TUBE SPRING Jun 14, 1927. 1,632,749

Filed 7 April 20, 1925 ATTORNEY Patented June 14, 1927 UNITED I STATES- Jonnc. SHAW, on BROOKLYN, NEW YORK, Assrenoiwo Ki LLnnMncnANIcAL ENGI- NEERING CORPORATION, or BROOKLYNQLNEW Yemen CGBPORATIOLN on NEW YORK.

BOURDON TUBE SPRING.

Application filed A ril 26, issa Serial No. 24,670.

My invention relates more particularly to a reinforcement for the Bourdon spring, to

prevent distortion or destruction of the tube by excessive gauge pressure. In pressure gauges subjected to high pressures,-1t may occur, occas onally, that excessive pressures are applied to the gauge which will expand the Bourdon tube beyond the elasticlimit of the material of the tube and givelt a set,

, sion and distortion of the Bourdon tube spring, so that it cannot exceed the elastic limit of the material of the tube and in this manner will protect the gauge. against destruction or defective readings.

Heretofore, where gauges are to be subjected to variable high pressures, it .has been the practice to thicken the walls of the tube to thereby protect the gauge, the thick walls preventing excessive pressures from distortjing or rupturing the tube, but obviously, this method decreases the sensitiveness of the gauge. A further object, therefore, of my improvement is to provide a plurality of muformly spaced substantially annular rein-- forcing devices preferably comprising a plurality of spaced rings extending throughoutthe length of the Bourdon spring and fitting loosely thereabout, the space between the rings and the wall of the tube being such that only a predetermined amount of er;-

pansion or distortion of the'tube will be permitted and this amount will be well within the elastic limit of the metal of the tube. This method of protection will permit the use of a comparatively thin walled tube, which will make for a greater sensitiveness in the gauge.

One from of my improvement is illustrated in the accompanying drawings, in which Fig. 1 is a plan view of a. Bourdon tube spring, Fig. 2 is a transverse section ofthe tube, showing the relation between the tube and the protecting rings surrounding the same; Fig. 3 is a partialview of the strip carrying provided with my improvement 3 and supportingthe protecting rings, and V F g. 4 showsone of the rings;

Referring to the drawings, A is a Bourdon tube spring, which may be of ordinary construction, and since the Bourdon spring is well known in the art, no further descrip tion thereof will be required. In the presentinstance, the Bourdon tube is preferably surrounded by a plurality of thin sheet metal rings B, uniformly'spaced apart throughout the effective length or the Bourdon tube spring, as indicated in Fig. 1 of the draw ings. 'Therings B are preferably"provided with laterally projecting lugs C, which ex tend through equally spaced punch holes in a metalstrip D, and are secured tothe PATE T- OFF C -j latter by heading over the lugs C, as indica ted at E in Fig. 2 of the drawings. Bourdon tube A is of the usual flattened construction, the flattening being radially of the curvature of the spring, as indicated in Fig. 2 of the drawings, and the rings B tit loosely thereabout. Thespace F between the fiattenedwalls of the Bourdon tube A and the rings B is preferably considerably greater than between the curved walls of the tube, as clearly indicated in Fig. 2 of the drawings. This space permits the Hour don tube to be distorted the normal predetermined amount, within the elastic limit of the material, after which the walls will c011- tact with the inner edges of the rings B and the latter will prevent any additional distortion, which under excessive or unusual pressure migl'it exceed the elastic limit of' the material of the tube A.

Obviously, this construction permits the use of a thinner walled Bourdon tube A,

the thickness of the walls being determined by the material used and the capacity of the gauge in which the Bourdon spring is to be used, and the sensitiveness required. Vhen these. factors have been determined, the rings B are proportioned to permit the maxiinun amount of expansion or distortion for the tube, that would berequired for the maximum reading of the gauge, and any excess pressure would be taken by the rings 13 and inthis manner the tube is protected from further distortion, which might result in rupturing or giving set to the tube. VVhen' the pressure is reduced, thelBourdon- The tube will again come back to normal because its elasticity has not been atfected and, therefore, the readings of the gauge will remain accurate, even though temporarily subjected to excessive pressures. Furthermore, as previously pointed out, the useof a thinner tubemakes for greater accuracy and sensitiveness in the gauge.

hile I have shown and descibed the preferred form of my improvement, it will be understood that I do not Wish to be limited to. the specific construction shown, for obviously, Various modifications in the specific construction may be made without departing from the spirit and scope of the invention.

Ifclaim:

1. A Bourdon tube spring reinforcement, comprising a Boar-don tube with a plurality ot'loosely fitting reinforcing ribs surrounding, the same andmeans for uniformly spacing, said ribs apart throughout the length thereof for limiting the expansion of the tube under pressure.

2. A Bourdontube spring reinforcement,

comprisinga Bourdon tube provided'with a plurality of thin sheet metal rings, loosely fitting the. tube and uniformly spaced apart.

throughout its length for preventing excessive expansion thereof, and means for holding said rings in spaced relation.

3. A Bout-don tube spring reinforcement, comprising a Bourdon tube. a plurality of thin metal rings surrounding and arranged tranyersely of the tube, said rings being slightly spaced from the wall of the tube, the spacing being greater on the flattened sides of the tube to thereby permit a predetermined amount of expansion of the tube, and means for holding said rings in spaced relation throughout the length of the tube.

a. A Bourdon tube spring reinforcement, comprising-a Bourdon tube, flattened radial- 1y of the curvature of the spring, a plurality of thin sheet metal rings surrounding said tube, the thin edges of said rings being in radial planes with respect to the center of the spring, said rings fitting the tube loosely and with a greater space betu'en the rings and the flattened sides of the tube to thereby permit a predetermined amount oi expansion, and means for holding said rings uniformly spaced apart throughout the length of the tube.

JOHN C. SI-LUY. 

